What does it take to have seamless Microsoft Windows file sharing and transfer capabilities on a *nix system? According to Sun Microsystems, it takes more than just Samba (define).

The company aims to follow a different approach to Windows file interoperability with its
new OpenSolaris CIFS Server (define) and client applications. Though developed by Sun, the server and client utilize Microsoft's Common Internet File System (CIFS) protocol, which is sometime referred to as SMB (Server Message Block) (define) and is the mechanism by which Windows files can be remotely accessed and transferred across a network.

"Our primary goal with this project was to add capabilities to make Solaris a stronger storage platform," Barry Greenberg, senior engineering manager, Solaris group at Sun told InternetNews.com. "If you truly want an integrated CIFS implementation that can really inter-operate with Windows at a fundamental level, the operating system has to support certain core features."

Sun's CIFS Server is an in-kernel implementation of the file sharing protocol and integrates with Solaris' underlying ZFS and NFS filesystems. The approach is somewhat different than that taken by Samba, which is currently supported by Solaris and shipped with most Linux operating systems.

"Samba, a user space implementation of the CIFS server, has limited ability to integrate with the underlying OS," Greenberg said. "The Solaris CIFS Server is a kernel-based implementation that allowed us the opportunity to extend the core Solaris file systems to accommodate Windows attributes and file access semantics."

"It also enabled us to do some interesting things to support Windows user identities directly in OpenSolaris, making it substantially easier to manage users and file access controls," he said.

Using CIFS also sidesteps another prickly issue: intellectual property.

The patents and intellectual property behind Samba technology have long been the subject of dispute between the open source community and Microsoft. In an 2006
interview with InternetNews.com, Microsoft's Bill Hilf, now general manager of Windows Server marketing and platform strategy, chatted about the company's IP concerns over Samba. Microsoft's patent covenant deal with Novell specifically lays out Samba as an area of interoperability.

Whether the companies also have agreements covering Microsoft for CIFS/SMB, however, is unclear.

"I know that Sun and Microsoft have a variety of agreements in place covering a variety of technologies, but I'm not aware of an arrangement specifically around CIFS/SMB," Greenberg said.

Microsoft representatives did not return requests for comment by press time.

At any rate, the CIFS Server comes as the latest OpenSolaris development build, though it's just an initial implementation.

"We still have a lot of work ahead of us to add CIFS features that were not achievable in the initial project and we will sharpen our focus on optimizing for the performance we expect to achieve with our in-kernel implementation."